Corrosion inhibitors containing amide surfactants for a fluid

ABSTRACT

A method of inhibiting corrosion in a fluid is disclosed. The method comprises: adding to the fluid an effective corrosion inhibiting amount of a synergist, a synergist when H 2 S is present in the fluid, or no synergist when H 2 S is present in the fluid, and a composition comprising specified following formula and optionally salts thereof.

FIELD OF THE INVENTION

The field of the invention pertains to corrosion inhibitors for a fluid,e.g. a fluid in an oil and gas pipeline or refinery.

BACKGROUND OF THE INVENTION

Corrosion of metal surfaces in a fluid has long been a problem for theoil and gas industry. Corrosion in the oil field produces a difficultintegrity management challenge for operators and with many fieldsoperating past their design life expectancies, it is extremely importantto control corrosion through the use of inhibitors. It is well knownthat during the production of oil and gas several other corrosivecomponents are present such as brines, organic acids, carbon dioxide,hydrogen sulfide, and microorganisms. Corrosivity to these systems isfurther magnified by species present in brines, such as organic acids,carbon dioxide (sweet systems), hydrogen sulfide (sour systems), and/ormicroorganisms, which causes a type of corrosion calledmicrobiologically influenced corrosion or MIC. Other factors that maypresent problems include high temperatures and pressures, high liquid orgas velocities, solid content, and metal composition. These aggressiveconstituents can cause severe corrosion to metal pipes, which are oftenmade of low-alloy steels. This problem is even more troublesome indeep-sea operations where replacement of corroded equipment is difficultand costly. Therefore, it is common practice to employ corrosioninhibitors during the production, transportation, storage, andseparation of crude oil and natural gas in order to maintain assetintegrity, prolong the service life, and protect the environment byreducing/eliminating failures in these systems.

Corrosion inhibitors are usually surface-active compounds that formprotective coatings on the surface of metal components, which come incontact with corrosive environments, and thus suppress corrosion.Corrosion inhibitors are compounds, which function to suppress thedeterioration of a substance (usually a metal) or its properties causedby reaction with its environment. This occurs as a result of adsorptionof the inhibitors to the metal surface, preferentially coating thesurface of the metal and forming of a protective film, which modifiesthe environment at the surface. Common corrosion inhibitors are composedof amines, condensation products of fatty acids with polyamines, e.g.imidazolines or polyamides, and quaternary ammonium compounds. Among themost frequently used corrosion inhibitors in crude oil and natural gasextraction are imidazoline derivatives.

Alternative corrosion inhibitors that can be used alone or incombination with known corrosion inhibitors are being sought by theindustry. Further to this point, because of the limited amount anddiversity of corrosion inhibitor actives currently available for use inthe oil field, newer, high performance, sustainable alternatives arebeing sought in the industry.

SUMMARY OF THE INVENTION

The present invention provides for a method of inhibiting corrosion in afluid comprising: adding to the fluid an effective corrosion inhibitingamount of a synergist, a synergist when H₂S is present in the fluid, orno synergist when H₂S is present in the fluid, and a compositioncomprising the following formula and optionally salts thereof:

where R₁ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; acrylate or H;where R₂ is a C₄-C₂₂ alkyl;where R₃ is C_(n)H_(2n+1), wherein n=0 to 12; benzyl; or H;where R₄ is C_(n)H_(2n+1), wherein n=0 to 22; or Hwhere X⁻ is an anion, halogen, a carboxylate, or a sulfate and whereinX⁻ is only present when both R₁ and R₃ are present;where Y═(CH₂)_(n), wherein n=1 to 8; andwherein R₃ and R₁ can not be hydrogen or n=0 at the same time.

DETAILED DESCRIPTION OF THE INVENTION

The methodology described above can have various embodiments.

In one embodiment, the compositions contain various amounts of differentcompositions that fall within the claimed formula.

In another embodiment, the fluid comprises water, gas, and optionallyliquid hydrocarbon.

In another embodiment, the alkyl groups of R₁ and/or R₂ and/or R₄ arelinear, branched, cyclic, and/or unsaturated or combinations thereof.

In another embodiment, R₃ is a methyl or ethyl group. When possible thealkyl groups can be linear or branched.

In another embodiment, the halogen is chlorine, bromine, or iodine. Thehalogen is in ionic form when it is associated with the composition.

In another embodiment, Y═(CH₂)_(n), wherein n=1 to 4. When possible thealkyl groups can be linear or branched.

In another embodiment, R₁ is a C₄-C₆ alkyl.

In another embodiment, R₂ is a C₆-C₁₈ alkyl.

In another embodiment, the composition contains the following formulaand optionally salts thereof:

where R₁ is C₄H₉, C₆H₁₃, C₈H₁₇, or benzyl;

where R₂ is a C₈H₁₇, C₁₂H₂₅, or C₁₈H₃₅;

where R₃ is CH₃ or C₂H₅;

where R₄ is C_(n)H^(2n+1), wherein n=0 to 22; or H

where X⁻ is an anion, halogen, a carboxylate, or a sulfate and whereinX⁻ is only present when both R₁ and R₃ are present;

where Y═(CH₂)_(n), wherein n=1 to 8; and

wherein R₃ and R₁ can not be hydrogen or n=0 at the same time.

In a further embodiment, Y═(CH₂)_(n), wherein n=1 to 2. When possiblethe alkyl groups can be linear or branched.

In another embodiment, the composition contains the following formulaand optionally salts thereof:

In another embodiment, the composition contains the following formula:

The composition is applied to a fluid that contains various levels ofsalinity.

In one embodiment, the fluid has a salinity of 1% to 20% weight/weight(w/w) total dissolved solids (TDS).

In another embodiment, the fluid has a salinity of greater that 0% toabout 5% w/w TDS. In a further embodiment, the water system is a transitline or a gas system.

The fluid to which the composition is applied to can contain variouslevels of water cut. One of ordinary skill in the art would interpretwater cut to mean the percentage of water in a composition containing anoil and water mixture.

In one embodiment, the water cut is from greater than 0% to 100%volume/volume (v/v).

In another embodiment, the water cut is from 1% to 60% v/v.

Various synthesis methodologies, which can be appreciated by one ofordinary skill in the art, can be utilized to make the claimedcompositions. These compositions are then utilized in methods ofinhibiting corrosion. The compositions can be made in the presence of asynergist.

In one embodiment, a composition is produced by reacting an alkylacrylate with 1-methylpiperazine and then subsequently reacting theresulting product with an amine to form an amide and reacting said amidewith an alkyl halide.

In a further embodiment, the amine is oleylamine.

In a further embodiment, the alkyl halide is 1-bromohexane.

The compositions of this invention can contain one or more additionalchemistries. Various formulations can be appreciated by one of ordinaryskill in the art and can be made without undue experimentation.

In one embodiment, the composition farther comprises one or more hydrateinhibitors.

In another embodiment, the composition further comprises one or morethermodynamic hydrate inhibitors, one or more kinetic hydrateinhibitors, one or more anti-agglomerants, or a combination thereof.

In another embodiment, the composition further comprises one or moreasphaltene inhibitors, paraffin inhibitors, corrosion inhibitors, scaleinhibitors, emulsifiers, water clarifiers, dispersants, emulsionbreakers, or a combination thereof.

In another embodiment, the composition further comprises one or morepolar or nonpolar solvents or a mixture thereof.

In another embodiment, the composition further comprises one or moresolvents selected from isopropanol, methanol, ethanol, heavy aromaticnaptha, toluene, ethylene glycol, ethylene glycol monobutyl ether(EGMBE), diethylene glycol monoethyl ether, xylene, kerosene, diesel,isobutanol, heptane, or a combination thereof.

The fluid in which the compositions and/or formulations are applied tocan be contained in many different types of apparatuses, especiallythose that transport a fluid from one point to another point, e.g. inone embodiment, the fluid is contained in an oil and/or gas pipeline.

In another embodiment, the fluid in which the compositions and/orformulations are applied to is in contact with many different types ofsurfaces that are capable of corrosion, e.g. those in an oil and gaspipelines/refineries, e.g. separation vessels, dehydration units, gaslines, and pipelines; and cooling water systems.

In another embodiment, the compositions and/or formulations are appliedto industrial water systems and/or municipal water systems.

The compositions of the present disclosure and/or formulations thereofcan be applied to a fluid in various ways that would be appreciated byof ordinary skill in the art. One of ordinary skill in the art wouldappreciate these techniques and the various locations to which thecompositions or chemistries can be applied.

In one embodiment, the compositions and/or formulations are pumped intothe oil/gas pipeline by using an umbilical line. In a furtherembodiment, capillary injection systems can be utilized to deliversurfactants, e.g. corrosion inhibitors. U.S. Pat. No. 7,311,144 providesa description of an apparatus and methods relating to capillaryinjection, which is herein incorporated by reference. Other manners ofinjection will be appreciated by one of ordinary skill in the art.

Various dosage amounts of a composition and/or formulation can beapplied to the fluid to control corrosion. One of ordinary skill in theart would be able to calculate the amount of corrosion inhibitor for agiven situation without undue experimentation. In one particularsituation, an effective amount is determined by supplying enoughchemistry to form a protective film of adequate thickness.

In one embodiment, the dose range for the corrosion inhibitor that isapplied to fluid, e.g. the fluid contained in an oil/gas pipeline, isbetween 0.1% volume to 2% volume based on water cut.

In a further embodiment, the dosages can be anywhere from 5 ppm to5,000-10,000 ppm depending on the application, e.g. batch or continuoustreatment.

Various types of synergists may be added to the fluid in combinationwith the composition(s) described above. One of ordinary skill in theart could appreciate how to formulate a synergist and the composition.

In one embodiment, a synergist, a synergist when H₂S is present in afluid, or no synergist when H₂S is present in the fluid, is added to thefluid with the compositions described above.

In a further embodiment, the fluid is contained in a production stream;in general, the fluid is the total liquid from production and this couldcontain oil, water, condensate, gas and combinations thereof which flowfrom the production tubing and are eventually collected in a separationfacility.

In another embodiment, the synergist can be a mercaptan, e.g.2-mercaptoethanol.

In another embodiment, the synergist formulation contains 3.5% v/v of2-mercaptoethanol and 20% actives of the corrosion inhibitor compositiondescribed above.

In another embodiment, the synergist is a sulfur-containing synergist.

In another embodiment, the synergist contains thioglycolic acid.

The examples are not meant to be limiting.

Examples

The wheel box test is a standard laboratory evaluation of corrosioninhibitor formulations used to compare the performance of potentialinhibitors in mitigating corrosion of carbon steel under sweetconditions. In theory, the test involves a simple weight lossmeasurement before and after the experiment to determine corrosionprotection of the chemical versus uninhibited samples. This allows thecorrosion inhibitors to be evaluated by their relative percentprotection. As can be seen below, each of the above examples exhibitscorrosion performance at dosages as low as 5 ppm, and each providesmoderate protection as the dosages approach 100 ppm.

TABLE 1 Wheel box test results for benzyl ammonium quaternarysurfactants Conc., % Example R₁ R₂ R₃ R₄ ppm Protection 1 C₆H₅CH₂-CH₃(CH₂)₄CH(CH₃)- CH₃- H 5 26.0 (Benzyl) 1-methyl hexyl (Methyl) 10 52.925 57.9 50 61.9 100 66.0 2 C₆H₅CH₂- CH₃(CH₂)₃CH(CH₂CH₃)CH₂- CH₃- H 534.1 (Benzyl) 2-ethyl hexyl (Methyl) 10 50.9 25 60.6 50 61.0 100 62.8 3C₆H₅CH₂- CH₃CH(CH₃)(CH₂)₃CH(CH₃)- CH₃- H 5 25.2 (Benzyl) 1,5-dimethylhexyl (Methyl) 10 56.7 25 58.3 50 58.1 100 62.4 4 C₆H₅CH₂-CH₃CH(CH₃)(CH₂)₂CH(CH₃)- CH₃- H 5 35.8 (Benzyl) 1,4-dimethyl pentyl(Methyl) 10 48.4 25 60.9 50 60.3 100 62.4Table 1 shows the corrosion protection profiles for Examples 1 to 4,which contain benzyl quaternary ammonium groups. These surfactants havedifferent alkyl groups on the R₂ position to investigate theirstructure-activity relationships. Each of the surfactants evaluatedexhibit moderate corrosion protection at the higher dosages of 25, 50,and 100 ppm. While it can be seen that Example #1 in table 1 providesthe greatest protection, each of these chemicals provide nearlyequivalent protection across the dosage range.

TABLE 2 Wheel box test results for butyl ammonium quaternary surfactantsConc., % Example R₁ R₂ R₃ R₄ ppm Protection 5 C₄H₉- CH₃(CH₂)₄CH(CH₃)-CH₃- H 5 35.3 (Butyl) 1-methyl hexyl (Methyl) 10 46.4 25 52.7 50 56.3100 58.0 6 C₄H₉- CH₃(CH₂)₃CH(CH₂CH₃)CH₂- CH₃- H 5 33.8 (Butyl) 2-ethylhexyl (Methyl) 10 43.2 25 50.4 50 54.2 100 56.5 7 C₄H₉-CH₃CH(CH₃)(CH₂)₃CH(CH₃)- CH₃- H 5 28.1 (Butyl) 1,5-dimethyl hexyl(Methyl) 10 36.0 25 47.1 50 53.3 100 56.0 8 C₄H₉-CH₃CH(CH₃)(CH₂)₂CH(CH₃)- CH₃- H 5 28.9 (Butyl) 1,4-dimethyl pentyl(Methyl) 10 43.2 25 46.3 50 51.8 100 54.1Tables 2, 3, and 4 give a comparison to quaternary ammonium surfactantscontaining pendant butyl, hexyl, and octyl groups respectively. Each ofthese examples gives comparable results for corrosion protection underthe laboratory conditions studied with one exception. Example 13 inTable 3 shows greater corrosion inhibition at 50 and 100 ppm as comparedto each of these examples. As one would expect, the oleyl group (C₁₈)provides enhanced performance due to the greater lipophilicity of thissurfactant as compared to other examples. This would suggest that longerchained alkyl groups, ranging from C12-C18, will provide greaterprotection than shorter alkyls and branched chains in the 5-6 carbonchain lengths. This is certainly confirmed in literature as the mostcommon corrosion inhibitors for use in the oil field are quaternaryammonium compounds and imidazolines containing longer alkyl chains withvarying degrees of unsaturation.

TABLE 3 Wheel box test results for hexyl ammonium quaternary surfactantsConc., % Example R₁ R₂ R₃ R₄ ppm Protection 9 C₆H₁₃- CH₃(CH₂)₄CH(CH₃)-CH₃- H 5 39.0 (Hexyl) 1-methyl hexyl (Methyl) 10 54.5 25 56.7 50 58.6100 59.7 10 C₆H₁₃- CH₃(CH₂)₃CH(CH₂CH₃)CH₂- CH₃- H 5 34.5 (Hexyl) 2-ethylhexyl (Methyl) 10 54.4 25 58.7 50 59.8 100 61.9 11 C₆H₁₃-CH₃CH(CH₃)(CH₂)₃CH(CH₃)- CH₃- H 5 35.4 (Hexyl) 1,5-dimethyl hexyl(Methyl) 10 51.4 25 54.6 50 58.4 100 60.8 12 C₆H₁₃-CH₃CH(CH₃)(CH₂)₂CH(CH₃)- CH₃- H 5 40.0 (Hexyl) 1,4-dimethyl pentyl(Methyl) 10 51.7 25 59.2 50 60.6 100 61.5 13 C₆H₁₃-CH₃(CH₂)₇CH═CH(CH₂)₈- CH₃- H 5 4.5 (Hexyl) Oleyl (Methyl) 10 60.7 2568.0 50 83.0 100 82.9

TABLE 4 Wheel box test results for octyl ammonium quaternary surfactantsConc., % Example R₁ R₂ R₃ R₄ ppm Protection 14 C₈H₁₇- CH₃(CH₂)₄CH(CH₃)-CH₃- H 5 6.8 (Octyl) 1-methyl hexyl (Methyl) 10 39.4 25 64.5 50 62.8 10066.1 15 C₈H₁₇- CH₃(CH₂)₃CH(CH₂CH3)CH₂- CH₃- H 5 3.7 (Octyl) 2-ethylhexyl (Methyl) 10 54.8 25 57.0 50 62.6 100 63.0 16 C₈H₁₇-CH₃CH(CH₃)(CH₂)₃CH(CH₃)- CH₃- H 5 26.2 (Octyl) 1,5-dimethyl hexyl(Methyl) 10 43.2 25 62.6 50 60.5 100 70.2 17 C₈H₁₇-CH₃CH(CH₃)(CH₂)₂CH(CH₃)- CH₃- H 5 32.6 (Octyl) 1,4-dimethyl pentyl(Methyl) 10 59.2 25 61.8 50 63.7 100 62.1

1. A method of inhibiting corrosion of metal surfaces in a fluidcomprising: adding to the fluid an effective corrosion inhibiting amountof a synergist, a synergist when H₂S is present in the fluid, or nosynergist when H₂S is present in the fluid, and a composition comprisingthe following formula and optionally salts thereof:

wherein R₁ is C_(n)H₂₊₁, wherein n=0 to 12; benzyl; acrylate or H;wherein R₂ is a C₄ to C₂₂ alkyl; wherein R₃ is C_(n)H_(2n+1), whereinn=0 to 12; benzyl; or H; wherein R₄ is C_(n)H_(2n+1), wherein n=0 to 22;or H wherein X⁻ is an anion, halogen, a carboxylate, or a sulfate andwherein X⁻ is only present when both R₁ and R₃ are present; whereinY═(CH₂)_(n), wherein n=1 to 8; and wherein R₃ and R₁ can not be hydrogenor n=0 at the same time.
 2. The method of claim 1, wherein the fluidcomprises water, gas, and optionally liquid hydrocarbon.
 3. The methodof claim 1, wherein R₃ is a methyl or an ethyl group.
 4. The method ofclaim 1, wherein the halogen is chlorine, bromine, or iodine.
 5. Themethod of claim 1, wherein Y═(CH₂)_(n), wherein n=1 to
 4. 6. The methodof claim 1, wherein R₁ is a C₄-C₈ alkyl.
 7. The method of claim 1,wherein R₂ is a C₆-C₁₂ alkyl.
 8. The method of claim 1 comprising thefollowing formula:

wherein R₁ is C₄H₉, C₆H₁₃, C₈H₁₇, or benzyl wherein R₂ is a C₈H₁₇,C₁₂H₂₅, or C₁₈H₃₅; wherein R₃ is CH₃ or C₂H₅; wherein R₄ is C_(n)H_(2n+1), wherein n=0 to 22; or H wherein X⁻ is an anion, halogen, acarboxylate, or a sulfate and wherein X⁻ is only present when both R₁and R₃ are present; wherein Y═(CH₂)_(n), wherein n=1 to 8; and whereinR₃ and R₁ can not be hydrogen or n=0 at the same time.
 9. The method ofclaim 8, where Y═(CH₂)_(n), wherein n is 1 to
 2. 10. The method of claim1, comprising the following formula and optionally salts thereof:


11. The method of claim 1 comprising the following formula:


12. A method of inhibiting the corrosion of metal surfaces in a fluidcomprising adding to the fluid an effective corrosion inhibiting amountof a synergist a synergist when H₂S is present in the or no synergistwhen H₂S is present in the fluid, and a composition produced by reactingan alkyl acrylate with 1-methylpiperazine and then subsequently reactingthe resulting product with an amine to form an amide and reacting saidamide with an alkyl halide.
 13. The method of claim 12, wherein saidamine is oleylamine.
 14. The method of claim 12, wherein the alkylhalide is a 1-bromohexane.
 15. The method of claim 1, wherein the fluidis in an oil field application.
 16. The method of claim 1, wherein thecomposition further comprises one or more hydrate inhibitors.
 17. Themethod of claim 1, wherein the composition further comprises one or morethermodynamic hydrate inhibitors, one or more kinetic hydrateinhibitors, one or more anti-agglomerates, or a combination thereof. 18.The method of claim 1, wherein the composition further comprises one ormore asphaltene inhibitors, paraffin inhibitors, corrosion inhibitors,scale inhibitors, emulsifiers, water clarifiers, dispersants, emulsionbreakers, or a combination thereof.
 19. The method of claim 1, whereinthe composition further comprises one or more polar or nonpolar solventsor a mixture thereof.
 20. The method of claim 1, wherein the compositionfurther comprises one or more solvents selected from isopropanol,methanol, ethanol, heavy aromatic naptha, toluene, ethylene glycol,ethylene glycol monobutyl ether (EGMBE), diethylene glycol monoethylether, xylene, kerosene, diesel, isobutanol, heptane, or a combinationthereof.